libstdc++-v3/config/os/gnu-linux/os_defines.h

   1 // Specific definitions for GNU/Linux  -*- C++ -*-
   2
   3 // Copyright (C) 2000-2025 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file bits/os_defines.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{iosfwd}
  28  */
  29
  30 #ifndef _GLIBCXX_OS_DEFINES
  31 #define _GLIBCXX_OS_DEFINES 1
  32
  33 // System-specific #define, typedefs, corrections, etc, go here.  This
  34 // file will come before all others.
  35
  36 // This keeps isalnum, et al from being propagated as macros.
  37 #define __NO_CTYPE 1
  38
  39 #include <features.h>
  40
  41 // Provide a declaration for the possibly deprecated gets function, as
  42 // glibc 2.15 and later does not declare gets for ISO C11 when
  43 // __GNU_SOURCE is defined.
  44 #if __GLIBC_PREREQ(2,15) && defined(_GNU_SOURCE)
  45 # undef _GLIBCXX_HAVE_GETS
  46 #endif
  47
  48 // Glibc 2.23 removed the obsolete isinf and isnan declarations. Check the
  49 // version dynamically in case it has changed since libstdc++ was configured.
  50 #define _GLIBCXX_NO_OBSOLETE_ISINF_ISNAN_DYNAMIC __GLIBC_PREREQ(2,23)
  51
  52 // Glibc 2.26 on i?86/x86-64/ia64/ppc64le added *f128 support.
  53 // Glibc 2.27 added it also on many other arches but those have IEEE quad
  54 // long double.
  55 #if __GLIBC_PREREQ(2, 26) \
  56     && (defined(__i386__) || defined(__x86_64__) || defined (__ia64__) \
  57         || (defined(__powerpc__) && defined(_ARCH_PWR8) \
  58             && defined(__LITTLE_ENDIAN__) && (_CALL_ELF == 2) \
  59             && defined(__FLOAT128__)))
  60 # define _GLIBCXX_HAVE_FLOAT128_MATH 1
  61 #endif
  62
  63 // Enable __cxa_thread_atexit to rely on a (presumably libc-provided)
  64 // __cxa_thread_atexit_impl, if it happens to be defined, even if
  65 // configure couldn't find it during the build.
  66 #define _GLIBCXX_MAY_HAVE___CXA_THREAD_ATEXIT_IMPL 1
  67
  68 #ifdef __linux__
  69 // The following libpthread properties only apply to Linux, not GNU/Hurd.
  70
  71 # if __GLIBC_PREREQ(2, 27)
  72 // Since glibc 2.27 pthread_self() is usable without linking to libpthread.
  73 #  define _GLIBCXX_NATIVE_THREAD_ID pthread_self()
  74 # else
  75 // Before then it was in libc.so.6 but not libc.a, and always returns 0,
  76 // which breaks the invariant this_thread::get_id() != thread::id{}.
  77 // So only use it if we know the libpthread version is available.
  78 // Otherwise use (__gthread_t)1 as the ID of the main (and only) thread.
  79 #  define _GLIBCXX_NATIVE_THREAD_ID \
  80    (__gthread_active_p() ? __gthread_self() : (__gthread_t)1)
  81 # endif
  82
  83 # if __GLIBC_PREREQ(2, 34)
  84 // Since glibc 2.34 all pthreads functions are usable without linking to
  85 // libpthread.
  86 #  define _GLIBCXX_GTHREAD_USE_WEAK 0
  87 # endif
  88 #endif // __linux__
  89
  90 #endif